package day14_21.day18;

import java.util.Scanner;

public class Main01 {
    public static void main(String[] args) {
        Scanner scn = new Scanner(System.in);
        int n = scn.nextInt();
        System.out.println(fun(n));
    }
    public static int fun (int n ){
        if (n == 1 || n == 2){
            return 1;
        }else {
            return fun(n - 1) + fun (n -2);
        }
    }
}
